1. Field of the Invention
Aspects of the invention relate to an electrode assembly and a secondary battery using the same, and more particularly, to an electrode assembly capable of increasing the capacity of a battery.
2. Description of the Related Art
Various batteries have been employed as power sources for electronic devices. Particularly, lithium secondary batteries have been widely used as power sources for small-sized electronic devices because they are compact and rechargeable, enable formation of high-capacity devices, and have high energy densities per unit area.
Formation of a lithium secondary battery may involve housing an electrode assembly in a cell case, injecting an electrolyte into the cell case, and sealing the cell case. The electrode assembly may be formed by stacking a positive electrode plate, a negative electrode plate, and a separator interposed therebetween and winding the stacked structure. Also, the positive electrode plate and the negative electrode plate may be obtained by coating active materials on a positive electrode collector and a negative electrode collector, respectively.
Lithium secondary batteries may be classified into a cylindrical type, a prismatic type, and a pouch type according to the external appearance of a cell case.
In general, an electrode assembly may be wound and wrapped with a tape so that the electrode assembly cannot unwind when fixedly housed in a cell case. Specifically, the tape may be attached to an outer circumferential surface of the electrode assembly in which a positive electrode plate, a separator, and a negative electrode plate are sequentially wound. The tape may wrap around a wound terminal portion of the outer circumferential surface of the electrode assembly. As known to those skilled in the art, the tape is typically called a finishing tape. However, use of the finishing tape may lead to an increase in the entire thickness of a secondary battery, thus hindering formation of a high-capacity secondary battery.
In order to form high-capacity secondary batteries without increasing the volume of a can, it is necessary to increase the amounts of positive and negative electrode active materials in the can. The amount of an electrolyte injected into the can should be increased according to the increase in the amounts of the positive and negative electrode active materials in order to ensure a predetermined lifespan.
Accordingly, a margin of an internal volume of the can (i.e., an area between the can and the electrode assembly) may be required to increase the amount of the electrolyte. However, since the finishing tape has a non-zero thickness, the margin of the internal volume of the can may be reduced according to the thickness of the finishing tape.